1. Field of the Invention
The present invention relates to polymerizable ethylenically unsaturated monomers containing benzotriazole groups and to polymers containing such groups.
2. Brief Description of the Prior Art
Acrylic polymers which are utilized as the resinous component for externally exposed plastics are often light sensitive and must be protected from ultraviolet light in order to prevent degradation of the polymer in the final product. Typically, materials known as ultraviolet light stabilizers are combined with the acrylic polymer to protect the polymer from the effects of ultraviolet light. A particularly well-known group of ultraviolet stabilizers are benzotriazole compounds, particularly those based on 2(2-hydroxyphenyl)2H-benzotriazole. However, UV light stabilizers of this type are often lost from the product into which they are incorporated by leaching or by evaporation.
To overcome these difficulties, efforts have been directed towards chemically incorporating the ultraviolet light stabilizer into the polymeric backbone of the material to be protected. A number of polymerizable ultraviolet stabilizers of the 2(2-hydroxyphenyl)2H-benzotriazole types have been synthesized. For example, 5-vinyl and 5-isopropenyl derivatives of 2(2-hydroxyphenyl)2H-benzotriazole and 4-acrylates or 4-methacrylates of 2(2,4-dihydroxyphenyl)2H-benzotriazole or 2(2,4-dihydroxyphenyl)1,3-2H-dibenzotriazole have been prepared and copolymerized with polymerizable alpha, beta-ethylenically unsaturated monomers to form acrylic polymers containing polymeric bound ultraviolet stabilizers. The 4-acrylates or 4-methacrylates of 2(2,4-dihydroxyphenyl)2H-benzotriazole, although being readily prepared and extremely reactive with other polymerizable alpha, beta-ethylenically unsaturated monomers, are suspect for the possibility of hydrolytic instability because of the presence of the aromatic ester group.
Therefore it is object of the present invention to prepare acrylate and methacrylate esters of 2(2-hydroxyphenyl)2H-benzotriazole derivatives where the 2(2-hydroxyphenyl)2H-benzotriazole units are connected to the acrylate or methacrylate groups by aliphatic ester linkages. These polymeric reaction products should have good hydrolytic stability.